Tension Clamp, Guide Plate and Fastening Point for Securing a Rail to a Ground Surface

ABSTRACT

The invention relates to a tension clamp for holding down a rail for rail vehicles. It includes a middle section with two legs, two torsion sections connected to the legs leading laterally outwards and having a support zone on their underside, by which the tension clamp is supported during use, and two supporting arms connected to the torsion sections. The supporting arms extend to the front side of the tension clamp and have a spring section and a support section, which has a support zone by which they are supported during use. The support sections of the supporting arms point laterally outwards so that the straight lines intersect in a region located on the rear side of the tension clamp. The invention also relates to a guide plate that protects a tension clamp against breakage during excitation in the range of its natural frequency, and a rail fastening point.

The invention relates to a tension clamp and a guide plate for fasteninga rail for rail vehicles.

Moreover, the invention relates to a fastening point in which a rail fora rail vehicle is fastened on a ground.

The ground on which a fastening point according to the invention isestablished is typically a sleeper or plate made of a solid materialsuch as concrete or similar. However, the fastening point according tothe invention can also be mounted on conventional wooden sleepersserving as the ground surface.

The rails fastened by means of the components and fastening points whichare improved by the invention usually have a rail foot, a rail webstanding on the rail foot and a rail head carried by the rail web.

Fastening points of the type in question here or the system comprisingcomponents in question here for the manufacture of such fasteningpoints, are known in many variants. Examples of such systems arepresented in the Applicant's published brochures, available for downloadfor example via the URLhttp://www.vossloh-fastening-systems.com/de/produkte_2015/anwendungsbereiche/conventional_rail/conventional_rail_thtml.The brochure “System W 41 U—Highly elastic rail fastening forconventional rail and high speed the universal solution for ballastedtrack with grooveless concrete sleepers”, as of September 2014, or thebrochure “System W 21—Highly elastic rail fastening for high speed andconventional rail the modern solution for ballasted track with concretesleepers”, as of February 2015.

The known rail fastening systems (see, for example, WO 2006/005543 A1and the other patent publications cited below) and rail fastening pointsproduced therefrom accordingly respectively typically comprise' ascomponents from which they are assembled, a guide plate (see, forexample, WO 2010/091725 A1), which is provided for laterally guiding therail, a W-shaped tension clamp provided for placement on the guide plate(see, for example, WO 2012/059374 A1) and a tension element (see, forexample, WO 2014/029705 A1), which is provided for clamping the tensionclamp against the ground surface (see for example WO 2006/005543 A1).

Along with these basic components of rail fastening systems,supplementary elements may also be respectively used, such as optionalshims (see, for example, WO 2011/110456 A1), which are used to adjustthe height of the rail above the ground or to distribute the loadsoccurring when passing over the rail by a rail vehicle, elasticintermediate layers (see WO 2005/010277 A1, for example), which arelikewise laid under the rail or the other plate-shaped components of thesystem in order to ensure a certain flexibility in the direction ofgravity for the rail in the fastening point formed respectively from thesystem, and insulator elements (see, for example, WO 2015/051 841 A1),which are typically located between the suspension element and the footof the rail to be fastened to ensure optimised electrical insulationagainst the ground surface.

The W- or ω-shaped tension clamps are usually one-piece and bent in onego from a spring steel wire. In this case, they have a usually V- orU-shaped middle section which has two legs aligned parallel to eachother. These legs define between them a free space through which therespective tension means, typically a sleeper screw or a bolt, is guidedinto the ground surface by means of its shaft. At one end, the legs areusually connected to each other via a base section which faces the railassociated with the front side of the tension clamp. At the other end ofthe legs of the middle section, however, a torsion section is typicallyrespectively formed, which emanates from the respectively associated legof the middle section, directed laterally outward.

In this case, the torsion sections are bent in the direction of theunderside of the tension clamp so that the suspension element can besupported during use on a support surface in the region of the torsionsections in a support zone formed on the respective torsion section,which is designed on the upper side of the component carrying thesuspension element, for example a guide plate. At their end facing awayfrom the middle section, the torsion sections usually merge respectivelyinto a supporting arm, which, when seen in a lateral view, is typicallycurved in an arc-like manner in the direction of the upper side of thetension clamp and, when seen in plan view, is aligned in the directionof the front side of the rail to be fastened. The free end sections ofthe supporting arms typically point in the direction of the middlesection. With these end sections, the tension clamp is supported duringuse on the foot of the rail to be fastened.

On the underside of the end sections support zones are formed, withwhich the end sections are supported on the rail foot during use. In thecase of the tension clamps known in practice, the support zones of thesupporting arms and the torsion sections are located regularly on astraight line which is aligned substantially parallel to the axis ofsymmetry of the tension clamp.

The elastic flexibility and thereby the hold-down force exerted on therail via the supporting arm can be adapted to the requirements andstresses that result in practical use, via the shape of the supportingarm as well as the form and alignment of its end sections. In the sameway, the spring behaviour of the tension clamp can be influenced by theshaping of the torsion sections and of the middle section as well as thetransition sections which may be present between the middle section andthe torsion sections as well as between the torsion sections and thesupporting arms.

The guide plates usually have on their upper side form elements on whichthe suspension element to be arranged on the respective guide plate isguided in such a way that, during use, it retains its position evenunder the loads occurring in practice. For this purpose for examplefillet-like depressions, in which the torsion sections of the suspensionelement are seated during use, or a central web can be formed on theupper side of the guide plate, on which the middle loop is guided andsupported.

It has been found that the lifespan of tension clamps depends cruciallyon their vibration behaviour. It is known that tension clamps usuallyhave several natural frequencies.

In practical use, the tension clamps are excited to vibrate when a trainpasses over the rail held down by the tension clamps. Periodicallyrecurring faults on the rail or on the wheels of rail vehicles can leadto resonance peaks. If these are close to one of the natural frequenciesof the tension clamp, there is a dramatic increase in the vibrationamplitude, in particular in the region of the supporting arms of thetension clamp. The result is a premature, sudden failure of the tensionclamp due to breakage, which typically occurs in the region of itstorsion sections or in the transition region of the supporting arms tothe torsion sections.

In an article published in the journal El-Der Eisenbahningenieur, August2016, page 25 ff., by Maximilian Steiger, studies on the optimisation ofthe dynamic behaviour of rail fasteners are reported. As a result ofthese studies, three measures for avoiding damage to rail fastenings dueto resonances have been proposed.

The first of the proposed measures comprises the arrangement ofvibration-damping additional elements on the tension clamp. These, forexample, disc or tube-like additional elements are to be arranged inparticular in the region of the supporting arms. However, the researchhas also shown that such vibration absorbers, while highly effective,are also destructive, so that the article comes to the conclusion thatthe practical usability of such absorbers is questionable.

As a second measure, the article has proposed an enlargement of thesupport surface provided for the tension clamp on the respective guideplate. Thus, the investigation has shown that increased resonances canincrease the natural frequencies of the tension clamps to such an extentthat they are outside the range in which they are typically excited inpractice. However, in practice the relative movements, which areperformed by the tension clamp and the guide plate when passing over therail laterally guided by the guide plate and held down by the tensionclamp, as a result of inevitable horizontal and vertical movements ofthe rail proved to be problematic. These movements led to increased wearin the region of the widened supports, which calls into question thefeasibility of the proposed support widening as a whole.

As a third measure, a change in the geometry of the tension clamp itselfwas finally proposed in the article. This measure also aims to increasethe natural frequency of the tension clamp to a range outside of theexcitement occurring in practice. The shape of the supporting arms andthe distance of the supporting arms to the so-called “tilt axis” of thesupporting arms has been recognised as a critical design feature. Thestraight lines have been designated as tilt axes of the supporting armsin this context, said lines connecting the centre of the zone with whichthe respective supporting arm is supported on the rail foot at its freeend during use, and the centre of the zone in which the respectivesupporting arm is supported with its other end on the guide plate. Thiszone is typically in the region of the torsion section assigned to therespective supporting arm. By reducing the distance to the tilt axis ofthe described arc of the supporting arms, e.g. a lowering of the heightof the arc over the guide plate, in turn the natural frequencies couldbe increased sufficiently.

However, the reduction of the geometry and in particular the arc heightof the supporting arms is accompanied by a fundamental change in theresilient properties. This can go so far that the tension clamp is nolonger optimally usable for the respective purpose or no longeroptimally fulfils the requirements placed on it with respect to itselastic behaviour.

Against this background, the object has arisen to identify practicalmeasures for the design of one or a plurality of interacting componentsfor a rail fastening point with the aim of maximising the life of thesystem formed from the components or of its individual components.

To achieve this object, the invention proposes the particular designs ofa tension clamp or guide plate which are generally disclosed in Claims 1and 7, wherein each of these design measures alone, i.e. isolated fromthe other measures, provides a solution to the above object and thusleads to an improvement in the vibration behaviour of the overall systemand in particular the tension clamp installed in this system. It goeswithout saying that the measures proposed here by the invention can becombined in any way with each other in order to develop an optimisedeffect.

Advantageous embodiments of the invention are defined in the dependentclaims and, like the general concept of the invention, are explained indetail in the following.

A fastening point according to the invention is accordinglycharacterised in that a tension clamp designed according to theinvention or a guide plate designed according to the invention areinstalled therein. Again, it goes without saying that the tension clampaccording to the invention and the guide plate according to theinvention respectively individually lead to a significant improvement inthe vibration behaviour, so can be used as alternatives to each other,but produce an optimal result when combined together.

A measure for improving the vibration behaviour of the tension clampitself, which is essential for the invention and particularly effectivein view of the issue addressed here, is thus, in each of the supportingarms of the tension clamp, to shift the zone with which the respectivearm is supported on the rail foot during use, such that the naturalfrequency is moved to a region in which it no longer causes vibrationalexcitation in practical use.

For this purpose, the invention proposes a tension clamp for elasticallyholding down a rail for rail vehicles, which comprises a foot, a webstanding on the foot and a rail head carried by the web, which in aconventional manner comprises

-   -   a loop-shaped middle section having two legs and a base section        connecting the legs to each other, wherein the free end face of        the base section faces the front side, the free upper side of        the middle section faces the upper side of the tension clamp and        the legs of the middle section, with their ends being remote        from the base section, face towards the rear side of the tension        clamp,    -   two torsion sections, one of which is connected respectively to        the end of one of the legs of the middle section, said end        facing away from the base section, wherein the torsion sections        lead laterally outwards respectively starting from their        respectively associated leg, and have a support zone on their        underside, by means of which the tension clamp is supported on        the component carrying it during use, and    -   two supporting arms, one of which is connected respectively to        the end of one of the torsion sections, said end facing away        from the associated leg of the middle section, wherein the        supporting arms extend in the direction of the front side of the        tension clamp and each have a spring section curved towards the        upper side of the tension clamp and also have an adjoining        support section ending at the free end of the supporting arm,        said support section comprising a support zone on its underside,        by means of which the respective supporting arm is supported        during use on the foot of the rail to be fastened.

According to the invention, the support sections of the supporting armspoint respectively laterally outward with respect to the middle sectionof the tension clamp, such that when viewed in plan view from above withrespect to the tension clamp, the straight lines, which respectivelyconnect the centre of the support zones of the supporting arms with thecentre of the support zone of the torsion section associated with therespective supporting arm, intersect in a region located on the rearside of the tension clamp.

Surprisingly, it has been shown that, in a tension clamp according tothe invention, the natural frequencies of the tension clamp can beeffectively increased so far that they lie outside of the excitationfrequencies that occur during practical use, in that the support zonesof the support sections of the supporting arms and the torsion sections,to which the respective supporting arm is connected, are no longerlocated on a line parallel to the axis of symmetry of the tension clamp,but on a straight line, which encloses an acute angle running in thedirection of the rear side of the tension clamp. Due to said invention,the durability of the tension clamp is significantly improved, withoutthis leading to a significant change in the resilience behaviour. Theinvention thus eliminates the problems encountered in the existingpractice, without a fundamental redesign of the components of a railfastening system being required.

Of course, the invention does not exclude that the measures proposed inthe prior art with regard to optimised dynamic behaviour of the tensionclamp (see, for example, the above-mentioned article by MaximilianSteiger) are also implemented in a tension clamp according to theinvention, based on the design according to the invention to achieve afurther optimised vibration behaviour. These include, in particular, thereduction in the amount of bending of the supporting arms over thesupport surface on which the tension clamp is mounted, and the increasein the support zones, with which the support sections of the supportingarms are seated on the rail foot during use.

When seen in plan view with respect to the tension clamp, the straightlines running through the centres of the support zones of therespectively associated support sections and torsion sections preferablyenclose an angle of at least 60°, in particular more than 60°, or atleast 90°, in particular more than 90°, in order to establish thegreatest possible distance between the natural frequencies of thetension clamp and a possible excitation frequency. With regard to theresilient action of the tension clamp, it has proved to be advantageousif the angle between the straight lines, seen in plan view with respectto the tension clamp, is a maximum of 120°, in particular less than120°.

For shifting the natural frequencies of a tension clamp according to theinvention, an additional optional design element may be used, in thatthe supporting arms, seen in plan view with respect to the tensionclamp, extend respectively outwardly away from the middle section,starting from their associated torsion section.

It also proves to be advantageous in view of the manufacturability anddurability of a tension clamp according to the invention, if, alsooptionally, the spring section of the supporting arms respectivelymerges into the associated support section in a continuous curve.

The following feature may further contribute to the durability andoptimal resilience behaviour of a tension clamp according to theinvention, if, also optionally, when viewed in plan view with respect tothe tension clamp, the support zones of the supporting arms project inthe direction of the front side of the tension clamp, with respect tothe free end face of the base section of the middle section.

A vibration behaviour of the tension clamps formed according to theinvention, which is particularly well adapted to the conditions inpractice, may occur if the following applies for the distance AS,measured parallel to the axis of symmetry of the tension clamp, betweenthe centre of the support zones of the supporting arms and theintersection of the straight lines, which respectively connect thecentre of the support zones of the supporting arms with the centre ofthe support zone of the torsion section associated with the respectivesupporting arm, and for the distance AG, likewise measured parallel tothe axis of symmetry, between the support zones of the supporting armsand the centre of the support zones of the torsion sections:

1.2×AG≤AS≤1.8AG.

It has proven to be particularly practical if:

1.3×AG≤AS≤1.7AG.

A guide plate according to the invention is provided with form elements,i.e. structural design features, which protect the supporting arms ofthe tension clamp arranged on the guide plate against excessivevibration amplitudes during use, which occur in the case of a vibrationexcitation in the range of one of the natural frequencies of the tensionclamp.

For this purpose, in a guide plate according to the invention forlaterally guiding a rail for rail vehicles in a rail fastening point,the rail comprising a foot, a web standing on the foot and a rail headcarried by the web, a support surface is provided on the free upper sidefor a tension clamp to be positioned on the guide plate, said tensionclamp serving to provide elastic holddown in the fastening point,wherein this clamp applies the elastic hold-down force via twosupporting arms, which are supported during use with their free endsections on the foot of the rail fastened in the fastening point.According to the invention, in such a guide plate at least two stops areprovided on the support surface, which limit at least the movements ofthe supporting arms of the tension clamp perpendicular to the contactsurface, when the tension clamp is positioned on the guide plate.

Should the tension clamp reach natural frequency during use, itssupporting arms hit against the stops provided on the guide plateaccording to the invention. These thus prevent the supporting arms fromperforming too large vibrations that could otherwise lead to breakage,even in a conventional tension clamp whose natural frequencies are notsufficiently far from the excitation frequency.

In order to catch the respective supporting arms safely when they comeinto contact with the stops, the stops can be designed in the manner ofsupports which carry on their respective free end face a fillet-likeseat for the associated supporting arm of the tension clamp.

In order to dampen the shocks associated with the striking of thesupporting arms on the stops, the stops have an elastic material ontheir free end face associated with the respective supporting arm of thetension clamp, said material serving to dampen a contact with theassociated supporting arm.

For a guide plate designed according to the invention, it is of coursealso understood that it may be expedient to implement measures tooptimise the dynamic behaviour, in addition to the inventive designproposed in the prior art (see, for example, the above-mentioned articleby Maximilian Steiger).

Thus, in order to shift the natural frequencies of a tension clampmounted on the guide plate according to the invention, it may bebeneficial to form depressions on the support surface in a guide plateaccording to the invention, the tension clamp being supported in thesedepressions during use by means of a respective section, and to coverthese depressions with a damping or elastic material in the region oftheir contact surfaces which come into contact with the tension clamp.This material may be formed as a separately manufactured insert or as alayer formed integrally bonded onto the material of the guide plate.

Likewise, it may be expedient to adapt the depressions to the shape oftheir respectively associated sections of the tension clamp, in such away that during use the section of the tension clamp seated in therespective depression tightly engages positively on the contact surfaceof the depression, at least over part of its length, so the contactlength between guide plate and tension clamp is increased. An optimisedeffect of this measure is obtained when the sections of the tensionclamp assigned to the depressions are torsion sections, which are bentin a continuous curve towards the underside of the tension clamp, andthe depressions are formed in an arc-like manner, corresponding to thecurve of the torsion sections, so that in a tension clamp positioned onthe guide plate the torsion sections are seated in the associateddepressions engaging tightly and positively over a partial length oftheir curve path. In the same way, it can have a positive effect on thedurability of a tension clamp arranged on the guide plate, if thesections have a damping or elastically yielding material in the regionof the depressions provided there for the support of the tension clamp.This material may also be formed as a separately manufactured insert oras a layer formed integrally bonded onto the material of the guideplate.

The guide plate is, as usual in the prior art, preferably made in onepiece out of a plastic, in particular a fibre-reinforced plastic.

As explained above, a fastening point according to the invention, inwhich a rail for a rail vehicle comprises a foot, a web standing on thefoot, and a rail head carried by the web, said rail being fastened to aground surface, has a guide plate acting against the lateral edge of thefoot of the rail for laterally guiding the rail and a tension clamppositioned on the guide plate, which is supported with the free endsections of its supporting arms on the foot of the rail, in order toexert an elastic hold-down force on the rail. The tension clamp or theguide plate are formed in accordance with the invention, wherein in thiscase it is also self evident that is possible for either only thetension clamp or only the guide plate to be formed in accordance withthe invention, but when both the guide plate and the tension clampcorrespond to the provisos according to the invention optimal resultsare achieved.

For clamping the tension clamp, a fastening point according to theinvention can comprise a tension element in a conventional manner, suchas a sleeper screw or a sleeper bolt, by means of which the tensionclamp is braced against the ground surface. The tension element inquestion is typically guided through the space delimited between thelegs of the middle section of the tension clamp, and through anunderlying opening of the guide plate down to the ground surface, whereit is anchored. The anchoring can be effected in a likewise conventionalmanner by means of a dowel recessed into the ground surface or anothersuitable fastening.

In order to protect the tension clamp installed in a fastening point fora rail of the type in question here, an insulating element may bearranged between the end sections of the supporting arms of the tensionclamp and the rail foot, which electrically insulates the tension clampagainst the rail and comprises dampening or elastically yieldingmaterial at least in sections. Thus, the insulator may be formed, forexample, as a sandwich element, in which electrically insulating layersare combined with damping or elastic layers, in order to achieve on onehand the required electrical insulation and on the other hand avibrational separation of the rail from the tension clamp, withsufficient resistance against the hold-down forces applied by thetension clamp. The measures referred to here relating to the insulatingelements already contribute in their own right, i.e. independently ofthe above-described inventive design features, to improving thedurability of the tension clamp used in a rail fastening point accordingto the invention, but of course are particularly advantageous in adesign according to the invention of a fastening point.

Another component that is used regularly in fastening points of the typein question here is an elastic intermediate layer which is usuallyarranged between the rail foot and the ground surface to give thesupport of the rail a certain flexibility in the direction of gravity.By adapting the damping behaviour of the elastic intermediate layer tothe excitation frequencies occurring in practice, it is also possible tocontribute to avoiding excessive excitation of the tension clamp in therange of its natural frequencies.

The invention is explained in more detail in the following withreference to a drawing representing, in diagrammatic form, an exemplaryembodiment, The schematic drawings show the following:

FIG. 1 shows a tension clamp according to the invention in plan viewfrom above.

FIG. 2 shows the tension clamp according to FIG. 1 in a perspective viewfrom its front side;

FIG. 3 shows the tension clamp according to FIGS. 1 and 2 in a sideview;

FIG. 4 shows a guide plate with a conventional tension clamp arrangedthereon in a perspective view from behind;

FIG. 5 shows the guide plate from FIG. 4 in a perspective view from thefront.

The tension clamp 1 according to the invention, shown in FIGS. 1-3, bentin one piece from a spring wire with a circular cross section, has aU-shaped middle section 2 with a curved base section 3 associated withthe front side V of the tension clamp and legs 4, 5, having a straightform, connected thereon. On the upper side of the legs 4, 5 of themiddle section 2 associated with the upper side O of the tension clamp1, flattened contact surfaces 6, 7 are provided, on which during use asleeper screw (not shown here) is seated by means of its screw head,serving as a tension element for tensioning the tension clamp 1.

At their ends facing away from the base section 3, and pointing to therear side R of the tension clamp 1, the legs 4, 5 of the middle section2 merge respectively into a torsion section 8, 9 of the tension clamp 1.The torsion sections 8, 9 are respectively bent in the direction of theunderside U of the tension clamp 1 and lead laterally outward away fromthe respectively associated leg 4, 5. On their underside, the torsionsections 8, 9 respectively have a support zone 10, 11, by means of whichthey are seated during use on a support surface of a guide plate.

At the end of the torsion sections 8, 9, respectively facing away fromthe middle section 2, a supporting arm 12, 13 is respectively connected.In the region of their spring sections 14, 15, the supporting arms 12,13 are designed to be curved in an arc-like manner respectively in thedirection of the upper side O of the tension clamp 1, and extendstarting from the respective torsion section 8, 9 in the direction ofthe front side V of the tension clamp 1. Thus, they are aligned suchthat, seen in plan view from above (FIG. 1), the distance of thesupporting arms 12, 13, measured parallel to the connecting lines Gbetween the centres Z10, Z11 of the support zones 10, 11, increasesstarting respectively from the torsion sections 8, 9.

At their free ends 16, 17, the supporting arms 12, 13 respectively endin a support section 18, 19, connecting on their respective springsection 14, 15, by means of which the supporting arm 12, 13 in theoperative condition is seated on the rail (not shown here) to befastened in the respective rail fastening point. On the underside of thesupport sections 18, 19 associated with the underside U of the tensionclamp 1, punctiform support zones 20, 21 are respectively formed theretoon the ends 16, 17 of the supporting arms 12, 13.

The support sections 18, 19 are formed pointing outwards from the middlesection 2 in a continuous curve starting from the respective springsection 14, 15, so that they conform tangentially to a straight linealigned parallel to the connecting line G. The length of the supportingarms 12, 13 is dimensioned so that the punctiform support zones 20, 21,when seen in plan view from above (FIG. 1), are located in front of thebase section 3 of the middle section 2 in the direction of the frontside V of the tension clamp 1.

Due to the outward-pointing arrangement of the support sections 18, 19and the punctiform support zones 20, 21 of the supporting arms 12, 13located correspondingly laterally outwards, the connecting lines G1, G2,which on the one hand (connecting line G1) connect the centre Z10 of thesupport zone 10 of the torsion section 8 with the punctiform supportzone 20 of the supporting arm 12 connected to the torsion section 8,said support zone thus itself representing the centre, and which on theon the other hand (connecting line G2) connect the centre Z11 of thesupport zone 11 of the torsion section 9 with the punctiform supportzone 21 of the supporting arm 13 connected to the torsion section 9,said support zone thus likewise itself representing the centre, arearranged at an acute angle β1 with respect to the axis of symmetry S ofthe tension clamp 1 and comprise an angle β2 of approx. 70°therebetween. Accordingly, when seen in plan view from above (FIG. 1),they intersect in a point of intersection SG located behind the rearside R of the tension clamp 1.

The distance AS, measured parallel to the axis of symmetry S, betweenthe punctiform support zones 20, 21 of the supporting arms 12, 13, saidsupport zones themselves forming the centre, on the one hand and theintersection SG on the other hand corresponds to approx. 1.5 times thedistance AG, also measured parallel to the axis of symmetry S, of thepunctiform support zones 20, 21 from the centres Z10, Z11 of the supportzones 10, 11 of the torsion sections 8, 9. In practice, the distance AGcan, for example, be approx. 100 mm and the distance AS approx. 150 mm,wherein the distance AS can be varied in the range of, for example, 130mm to 170 mm, if this is expedient in terms of setting the naturalfrequencies or due to structural conditions.

Practical tests have shown that the tension clamp 1 has naturalfrequencies of at least 50% higher compared with a conventionally shapedtension clamp 101 shown in FIGS. 4 and 5. These are so high that evenunder unfavourable conditions of use, as may be the case for example intunnels or on bridges, there is no excitation of the tension clamp 1 inthe range of its natural frequencies.

The tension clamp 101 shown in FIGS. 4 and 5, arranged on a guide plate100, has a U-shaped middle section 102 with legs extending parallel toeach other, which merge respectively into a torsion section 108, 109leading laterally outwards from the middle section 102 and bent towardsthe underside U of the tension clamp 101. The torsion sections 108, 109also respectively have a support zone on their underside, with whichthey are seated on the guide plate 100 during use.

Thus a supporting arm 112, 113 is also respectively connected to itsspring section 114, 115, curved upwards in an arc-like manner, on thetorsion sections 108, 109. In contrast to the tension clamp 1 accordingto the invention, however, in the case of the tension clamp 101, thesupport sections 118, 119 of the tension clamp 101 ending at the freeends 116, 117 of the supporting arms 112, 113 are bent in the directionof the middle section 102, so that the ends 116, 117 of the tensionclamp 101 directed towards one another and the connecting lines G1′,G2′, which respectively interconnect the punctiform support zones of thesupporting arms 112, 113 to the centre Z110, Z111 of the support zoneson the respective associated torsion section 108, 109, are alignedparallel to the axis of symmetry S′ of the tension clamp 101.

In the case of the conventionally shaped tension clamp 101, in order toprevent damage as a result of excessive vibration movements as a resultof excitation in the natural frequency range, stops 126, 127 areprovided on the support surface 125, which is configured on the upperside of the guide plate 101 formed integrally of a plastic approved forthis purpose, said stops being formed in the manner of supports. Thestops 126, 127 are arranged in the region of the greatest height of therespective spring section 114, 115 of the tension clamp 101 and carry attheir free frontal end respectively a U-shaped receptacle 128, 129,whose dimensions are proportioned so that the respective spring section114, 115 is seated positively in the respective receptacle 128, 129, inthe event that it comes into contact with the associated stop 126, 127.In order to dampen the contact, the receptacle is designed with ashock-absorbing material. The height position of the receptacles 128,129 is selected to be such that the spring sections 114, 115 can performthe elastic movements required during normal operation, but aresupported in the receptacles 128, 129 in the event of an excessiveexcitation exceeding those movements which are to be expected duringnormal operation.

With the support zones Z110, Z111 provided in the region of theirtorsion sections 108, 109, the tension clamp 101 is seated respectivelyin a depression 130, 131 formed in the support surface 125 of the guideplate 100. The depressions 130, 131 are designed in elevations 132, 133formed on the contact surface 125. Their size, thickness and height isdesigned so that the arc length BL, which comprises a contact betweenthe respective torsion section 108, 109 and the guide plate 100, issubstantially greater than the approximately punctiform contact, whichwould be between the torsion sections 108, 109, if this were to besupported on a level support surface. The purpose of the depressions130, 131 being configured in the elevations 132, 133 is that theposition of the torsion sections 108, 109 is the same with respect tothe support surface 125 as in the case of a support on a flat supportsurface 125, despite their being seated in the depressions 130, 131. Thedepressions 130, 131 are also designed with a suitable damping materialto dampen the vibrations of the tension clamp 101.

REFERENCE NUMERALS

-   1 Tension clamp-   2 Middle section of the tension clamp 1-   3 Base section of the middle section 2-   4, 5 Legs of the middle section 2-   6, 7 Contact surfaces of the legs 4, 5-   8, 9 Torsion sections of the tension clamp 1-   10, 11 Support zones of the torsion sections 8, 9-   12, 13 Supporting arms of the tension clamp 1-   14, 15 Spring sections of the supporting arms 12, 13-   16, 17 Free ends of the supporting arms 12, 13-   18, 19 Support sections of the supporting arms 12, 13-   20,21 Punctiform support zones (=centre of the support zones 20, 21)-   G, G1, G2 Connecting lines-   Z10, Z11 Centres of the support zones 10, 11-   β1, β2 Angles-   S Axis of symmetry of the tension clamp 1-   100 Guide plate-   101 Tension clamp-   102 U-shaped middle section of the tension clamp 101-   108, 109 Torsion sections the tension clamp 101-   112, 113 Supporting arm of the tension clamp 101-   114, 115 Spring sections of the supporting arms 112, 113-   116, 117 Free ends of the supporting arms 112, 113-   118, 119 Support sections of the tension clamp 101-   125 Support surface of the guide plate 100-   126, 127 Stops-   128, 129 U-shaped receptacles (=seat)-   130, 131 Depressions-   132, 133 Elevations-   BL Arc length over which there is contact between the respective    torsion section 108, 109 and the guide plate 100-   G1′, G2′ Connecting lines-   Z110, Z111 Centre of the support zones of the torsion sections 108,    109-   S′ Axis of symmetry of the tension clamp 101-   AG, AS Distances-   O Upper side of the tension clamps 1, 101-   U Underside of the tension clamp 1, 101-   R Rear side of the tension clamp 1, 101-   SG point of intersection-   V Front side of the tension clamp 1, 101

1. A tension clamp for elastically holding down a rail for railvehicles, said rail comprising a foot, a web standing on the foot and arail head carried by the web, the tension clamp comprising: aloop-shaped middle section, which has two legs and a base sectionconnecting the legs to each other, wherein a free end face of the basesection faces a front side, a free upper side of the loop-shaped middlesection faces the free upper side of the tension clamp and the legs ofthe loop-shaped middle section, with their ends being remote from thebase section, face a rear side of the tension clamp; two torsionsections, one of which is connected respectively to an end of one of thelegs of the loop-shaped middle section, said end facing away from thebase section, wherein the torsion sections lead laterally outwardsrespectively starting from their respectively associated leg, and have asupport zone on an underside, by means of which the tension clamp issupported on a component carrying it during use; and two supportingarms, one of which is connected respectively to an end of one of thetorsion sections, said end facing away from the associated leg of theloop-shaped middle section, wherein the supporting arms extend in thedirection of a front side of the tension clamp and each have a springsection curved towards the free upper side of the tension clamp and alsohave an adjoining support section ending at a free end of the supportingarm, said support section comprising a support zone on its underside, bymeans of which the respective supporting arm is supported during use onthe foot of the rail to be fastened, wherein the support sections of thesupporting arms each point laterally outwards with respect to theloop-shaped middle section of the tension clamp in such a way that, whenseen in plan view from above with respect to the tension clamp, straightlines, which respectively connect a center of the support zones of thesupporting arms with a center of the support zone associated with theirrespective supporting arm, intersect in a region located on the rearside of the tension clamp.
 2. The tension clamp according to claim 1,wherein between the straight lines an angle is enclosed, which is atleast 60° when seen in plan view with respect to the tension clamp. 3.The tension clamp according to claim 1, wherein the angle enclosedbetween the straight lines is at most 120°, when seen in plan view withrespect to the tension clamp.
 4. The tension clamp according to claim 1,wherein the supporting arms, when seen in plan view with respect to thetension clamp, run respectively outwardly away from the loop-shapedmiddle section, starting from their associated torsion section.
 5. Thetension clamp according to claim 1, wherein in the supporting arms, thespring section merges respectively into the associated support sectionin a continuous curve.
 6. The tension clamp according to claim 1,wherein the support zones of the supporting arms, when seen in plan viewwith respect to the tension clamp, extend in a direction of the frontside V of the tension clamp relative to the free end face of the basesection of the loop-shaped middle section.
 7. The tension clampaccording to claim 1, wherein for the distance AS, measured parallel toan axis of symmetry of the tension clamp, between the center of thesupport zones of the supporting arms and the intersection of thestraight lines, which respectively connect the center of the supportzones of the supporting arms with the center of the support zone of thetorsion section associated with the respective supporting arm, and forthe distance AG, also measured parallel to the axis of symmetry of thetension clamp, between the support zones of the supporting arms and thecenters of the support zones of the torsion sections, the followingapplies:1.2×AG≤AS≤≤1.8AG.
 8. The tension clamp according to claim 7, wherein forthe distance AG and the distance AS, the following applies:1.3×AG≤AS≤1.7AG.
 9. A guide plate for laterally guiding a rail for railvehicles in a rail fastening point, the rail comprising a foot, a webstanding on the foot and a rail head carried by the web, wherein asupport surface is provided on a free upper side of a tension clampwhich is positioned on the guide plate, said tension clamp serving toelastically hold down the rail in the fastening point, wherein thetension clamp applies an elastic hold-down force over two supportingarms, which are supported during use with the two supporting arms' freesupport sections on the foot of the rail fastened in the fasteningpoint, wherein at least two stops are provided on the support surface,which limit at least the movements of the supporting arms of the tensionclamp perpendicular to a contact surface, when the tension clamp ispositioned on the guide plate.
 10. The guide plate according to claim 9,wherein the stops are designed in the manner of supports, whichrespectively carry at their free end face a fillet-like seat for theassociated supporting arm of the tension clamp.
 11. The guide plateaccording to claim 9, wherein the stops have respectively an elasticmaterial on their free end face assigned to the respective supportingarm of the tension clamp, said material dampening a contact with theassociated supporting arm.
 12. The guide plate according to claim 9,wherein on the support surface depressions are formed, in which thetension clamp is respectively supported during use with a section, andin that the depressions are covered with a damping or elastic materialin the region of their contact surfaces, which come into contact withthe tension clamp.
 13. The guide plate according to claim 12, whereinthe depressions are adapted to the shape of the respectively associatedsections, of the tension clamp such that during use the section of thetension clamp seated in the respective depression engages positively onthe contact surface of the depression at least over a part of itslength.
 14. The guide plate according to claim 12, wherein the sectionsof the tension clamp assigned to the depressions are torsion sections,which are bent in a continuous curve towards an underside of the tensionclamp, and in that the depressions are correspondingly arc-shaped in thecourse of the torsion sections, so that the torsion sections engagepositively and tightly over a partial length of their tension curve whenthe tension clamp is positioned on the guide plate, and are seated inthe associated depression.
 15. A fastening point in which a rail for arail vehicle is fastened on a ground surface, the rail comprising afoot, a web standing on the foot and a rail head carried by the web,wherein the fastening point comprises a guide plate acting against alateral edge of the foot of the rail for laterally guiding the rail anda tension clamp positioned on the guide plate, said tension clamp beingsupported by means of free support sections and supporting arms on thefoot of the rail, in order to apply an elastic hold-down force on therail, wherein the guide plate is designed according to claim
 9. 16. Thefastening point according to claim 15, wherein the fastening pointcomprises a tension element, such as a sleeper screw or a sleeper bolt,by means of which the tension clamp is braced against the ground. 17.The fastening point according to claim 15, wherein an insulating elementis arranged between the support sections of the supporting arms of thetension clamp and a rail foot, in that this insulating element insulatesthe tension clamp electrically with respect to the rail foot and, atleast in sections, comprises a damping or an elastically yieldingmaterial.